Synthesis and enzymic hydroxylation of protocollagen model peptide containing a hydroxyproline residue

1. Two protocollagen model peptides, Z-Gly-Pro-Hyp-Gly-(Pro-Pro-Gly)(5) (Z, benzyloxycarbonyl) and AOC-(Pro-Pro-Gly)(6) (AOC, tert.-pentyloxycarbonyl), were synthesized and hydroxylated with protocollagen proline hydroxylase. 2. The two model peptides were hydroxylated equally. The results suggest that the hydroxyl group of hydroxyproline contained in the N-terminal region of the peptide has no effect on the enzymic hydroxylation of the model peptide.

Cerebral atherosclerosis in Japanese. I. Age related to atherosclerosis

During a period of approximately two years (1965 through 1966), 717 intracranial cerebral arteries (males and females) were obtained from the medicolegal autopsy cases. Systematic grading of the macroscopic severity of cerebral atherosclerosis was performed and the results were reported. In general, cerebral atherosclerosis appeared as early as the second decade and increased in severity with age, particularly at the fifth decade in males and the sixth decade in females. The prevalence of localization of early and/or severe cerebral atherosclerosis was studied. The results in the present study were not the same as in the previous investigations on Caucasians. The common sites of the severe cerebral atherosclerosis causing marked lumen narrowing were the proximal portion of posterior cerebral arteries, peripheral portion of the middle cerebral arteries, and the vertebral arteries and their fusing site at the basilar artery; the internal carotid artery was the least commonly involved.

In the present study, the influence of sex in the production of cerebral atherosclerosis was suggested, and the simple senescence theory of cerebral atherosclerosis was not supported. The macroscopic severity of cerebral atherosclerosis of Japanese in the present study appeared to be equal to or slightly greater than that in Americans and Norwegians reported by Baker et al.

The enzymic hydroxylation of protocollagen models

1. Synthetic polymers of l-prolyl-l-prolylglycine of defined chain length, (Pro-Pro-Gly)(n), were found to be substrates for the enzyme protocollagen-proline hydroxylase, with optimum chain length n=5. Boiling the polymer (Pro-Pro-Gly)(15) increased its activity as a substrate but had no effect on (Pro-Pro-Gly)(5). 2. Protection of both or one of the N- and C-terminal groups made (Pro-Pro-Gly)(3) a better substrate, and collagenase digestion of hydroxylated tert.-pentyloxy-carbonyl-(Pro-Pro-Gly)(3) benzyl ester indicated that the central prolyl residues were the major points of hydroxylation. 3. The results suggest that the long-chain peptides are optimum substrates but that a triple-stranded structure is inhibitory for hydroxylation.